Field of the Disclosure
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on.
Description of Related Art
Wireless communications systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems. Generally, a wireless multiple-access communications system may include a number of base stations, each simultaneously supporting communication for multiple user devices. Base stations may communicate with user devices on downstream and upstream links. Each base station has a coverage range, which may be referred to as the coverage area of the base station or cell.
User devices that are proximate to each other may also communicate directly via device-to-device (D2D) communication. In order to do so, however, a user device first discovers the other user devices that are within range for D2D communication. The process of D2D discovery allows a user device to transmit a discovery signal so as to announce that the user device is available to be discovered. Additionally, the user device receives and decodes discovery signals from other user devices that are within range. However, in order for a D2D transmission to be received and decoded, the receiving user devices may need to have an understanding of the timing and method by which the transmitting user device is broadcasting its discovery signal.